This invention relates to flexible hose having spring inserts in the passageway thereof, such as corrugated hose with internal convolutions in which turns of the coiled insert are retained.
Various flexible automotive and industrial hoses, such as radiator hose and air brake hose incorporate spring inserts of annular or spiral corrugated form to resist collapse of the hose under reduced pressures or bending. The hoses usually have a textile knit, braid or other reinforcement to withstand elevated internal pressures. For instance, in an automotive radiator hose application, temperatures typically may reach about 270 degrees F., and internal pressures rise to about 20 psig. Under these conditions, with typical knit reinforcement members embedded in the hose wall, the hose may swell (radially) from about 4 to about 15 percent. This enlargement of the hose may in turn lead to disengagement of the coiled insert from the corrugations formed in the internal passageway of the hose. The coiled spring may migrate to the extent of being fully expelled from the hose and in the case of an automotive cooling system lodge itself in the thermostat, water pump impeller or other area causing damage.
It is an object of the present invention to provide means of simple construction for preventing enlargement of the hose along an intermediate portion thereof and to thereby ensure retention of the spring insert within the hose. It is another object to provide an inexpensive method for achieving the improved hose construction.